Sequoia Scientific


Submersible Digital Holographic Camera

The LISST-Holo2 stores holograms for study of flocs, plankton, and other particles in water.

Holograms are captured at up to 25 Hz. The instrument is powered from an internal, rechargeable battery and the on-board memory can hold ~110,000 holograms. Processing speed per unit water volume imaged is faster than the competition.

Application areas for the LISST-Holo2 are diverse and includes sediment & flocculation studies, algae & plankton studies, frazil ice formation, aeolian sediment transport and more.

Click here to watch a video on Sequoia’s fast hologram processing software.


  • In-situ digital in-line holographic technology
  • Self-contained with internal datalogger and rechargeable battery
  • Ethernet connection to PC for programmable data collection—no software needed for programming or offloading data
  • Power via internal rechargeable battery pack or external power source
  • Programmable data collection including burst and fixed Rate modes and programmable start and stop conditions
  • Automated firmware updates possible when instrument is connected to the Internet
  • Automated ranking of collected images based on richness of data, permitting a user to view the most interesting holograms first
  • Data processing yields in-focus particle images and particle volume distribution
  • Optical Path Reduction Modules available for higher concentration ranges
  • Towable up to 4 knots (2.05 m∙s-1)

Figures below: (left) Watch the slider at bottom indicating the location of plane where image is focused; different particles come into focus at different distances from the optical window; axes are in microns, and (right) a collection of images, courtesy of Dr John Ryan, MBARI.



(Specifications are subject to change)

Parameters Measured

  • 2MB Hologram containing the interference pattern of all particles in the laser beam
  • Depth
  • Temperature
  • Time-stamp on each hologram

Parameters derived upon hologram processing

  • Reconstructed in-focus images of particles in laser beam.
  • Particle Size Distribution (PSD)
  • Standard Deviation of PSD
  • Particle Area Concentration
  • Mean and Median particle size
  • 5 seconds processing time per 1 cm 3 volume imaged, in MATLAB (typical, @ 2.2 GHz PC)

Particle Size Distribution and concentration range

  • ~25-2500µm size range
  • Beam attenuation values between 0 and 4 m-1
  • Maximum concentration between 0 and 50 mg/l, depending on grain size. 


  • Solid state laser diode @ 658 nm, 8 mW
  • 4.4µm pixel size digital camera, 1600 x 1200 pixels
  • 2 MB hologram size
  • Hologram capture rate programmable up to 25 per second continuous;
  • Optical path length 50 mm standard; Path reduction modules available for high-concentration environments.
  • All particles in focus in optical path.
  • Sampling volume per hologram 1.5 cm 3
  • Volume sampled per second at 25Hz sample rate: 37.5 cm 3
  • Maximum current velocity/CTD speed during deployment: 2 m s -1 


  • Holo Batch: Automated image reconstruction and particle segmentation
  • Holo Detail: Hologram sorting by richness of information content, and detailed reconstructed image examination.

Mechanical and Electrical

  • Dimensions: 13.3 cm × 76.7 cm (5.25″ × 30.21″) [Ø × L]
  • Weight: 7.2 kg (15.8 lbs) in air; 1.0 kg (2.2 lbs) in water
  • 600 m depth rating
  • 237 GB internal solid state drive
  • Internal Battery life: at least 12 hours of continuous use.
  • External power input: 18VDC nominal, 12-24VDC
  • Power drain: 200µA / 700mA / 800mA / 800mA (sleeping / idling / laser on / laser + camera on)


LISST-Holo2 Item # and Description

Item #DescriptionThumbnail
SEQ-FP-LHO2LISST-Holo2 Submersible Digital Holographic Camera
25-2500 um size range, 600 m depth rating. Includes internal data logger with 237 GB storage, internal rechargeable NiMH battery, integrated depth and temperature sensor, 110/220 VAC power supply, 2 m power cable, 2 m Ethernet communication cable, 2 m pigtail for connection to external power source, small volume test chamber, flow through chamber, Path Reduction Module (PRM), Pelican shipping container with custom foam cushioning, Windows software for hologram reconstruction and image analysis.
LISST-Holo Digital Holographic Imaging System
Must be purchased together with new instrument.
No picture
One-time service of instrument within 36 months after delivery.
Includes one-way return shipping from Sequoia, all evaluation, diagnosis, testing and calibration.
Parts and labor for repairs not included.
Must be purchased together with new instrument.
NOTE: End-user responsible for return shipment DDP to Sequoia.
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LISST-Holo Upgrade Options

Item #DescriptionThumbnail
SEQ-AC-LHO2-UPGUpgrade of original LISST-Holo to LISST-Holo2
Upgrade the original LISST-Holo to a LISST-Holo2 with full capabilities. Includes replacement of all electronics, camera, Connector endcap including all underwater connectors, depth sensor, temperature sensor. Assumes that the optics end and main pressure case, internal optics and laser and shipping case can be reused.

LISST-Holo2 Accessories *NOT INCLUDED* with LISST-Holo2

Item #DescriptionThumbnail
SEQ-AC-LHO2-FRMMounting Frame for LISST-Holo2
316 s/s frame. Includes bridle and instrument mounting clamps.
SEQ-AC-LHO-EBPExternal battery housing for the LISST-Holo / LISST-Holo2
Includes 20 standard Alkaline D-cells installed, connecting cables and cardboard shipping container. Similar to LISST-200X Large External Battery Pack with the addition of 4 D-cells for a higher voltage battery pack.
NOTE: The LISST-Holo2 has an internal rechargeable battery and DOES NOT require an external battery. However, the External Battery can be used to supplement the internal battery for extended deployments.
LISST-Holo2 external battery housing

LISST-Holo2 external battery housing

LISST-Holo2 Accessories *INCLUDED* w/ LISST-Holo2

Item #DescriptionThumbnail
SEQ-AC-LHO-CHFPFull Path Flow Through Chamber for LISST-Holo2 / LISST-Holo
Slip on chamber which allow LISST-Holo2 to be used in a flow through mode in the lab or under water. Includes multiple sized barb fittings.
LISST-Holo Flow Through Chamber

LISST-Holo Flow Through Chamber

SEQ-AC-LHO-CHZSTest Chamber for LISST-Holo2 / LISST-Holo
For laboratory measurements with standard 5 cm path LISST-Holo2 / LISST-Holo instruments.
NOTE: One chamber ships as standard with all new LISST-Holo2 instruments.
LISST-100X zscat chamber

LISST-100X zscat chamber

SEQ-AC-LHO-PRMOptical Path Reduction Module for the LISST-Holo2 / LISST-Holo
Reduces the optical path length to 25 or 10 mm (50 or 80% reduction) depending on the width of the spacer. Two spacers, one for 25 mm path and one for 10 mm path are included.


SEQ-AC-LHO2-CBL022 m cable for power ONLY. No data.
SEQ-AC-LHO2-RJ45-1M1 m Ethernet cable for data ONLY. No power.

LISST-Holo2 custom length cables

NOTE: To order any cable, order qty 1 base item #, and qty xx cable item #, where xx is cable length in integer m.
E.g., to order a 45 m cable for powering a LISST-Holo2 via a power brick, order:

In Holo2, unlike the other instruments, USB and serial connections are used only for troubleshooting through the Linux command line. Main communication for data and control is through Ethernet.
The ethernet cable item # is SEQ-AC-LHO2-RJ45-CBL. To transfer data over an, e.g., 45 m cable you must ALSO order qty 45 x SEQ-AC-LHO2-RJ45-CBL in addition to the 45 m power cable specified above.
Base Item #Topside ConnectionCable Design
SEQ-AC-LHO2-CBLBCable base for LISST-Holo2 power *only*.
Power brick for external power (19V) included.
Order w/ xx m of SEQ-AC-LISST-CBLY
No Picture
SEQ-AC-LHO2-RJ45-CBLComplete custom length Ethernet cable for LISST-Holo2 data transfer ONLY.
Specify length in m when requesting a quote or ordering.
No picture
Cable Item #DescriptionThumbnail
SEQ-AC-LISST-CBLYYellow submersible cable. Reinforced.
Must order with


How does the LISST-Holo2 work?

The LISST-Holo2 contains a red (658nm) laser that emits collimated light into the sample volume. The light is scattered by suspended particles. The scattered light then interferes with the unscattered portion of the beam. The resulting interference pattern is captured by an onboard camera. The image captured by the camera is known as a hologram.

The hologram can be digitally reconstructed to produce an in-focus picture of all the particles in the sample volume. Information about the particles size, shape, and position can all be extracted from the hologram.

How is the LISST-Holo2 different from an in-situ microscope?

The LISST-Holo2 is similar to a microscope in that it can produce in-focus images of small suspended particles. However, the benefit of using a holographic system is that you can have a large sample volume while still maintaining proper focus. In traditional microscopes, increasing the magnification decreases the depth of field. Thus, you can only image a thin slab of water. In holography the depth of field problem is eliminated, because each particle can be focused individually after the hologram has been captured.

The larger depth of field allows for a larger sample volume than is possible with a traditional microscope. This has two benefits. (1) It allows for more particles to be imaged, which will statistically improve the size distribution measurement. (2) It allows for a larger gap between the send and receive optics. The larger spacing is less likely to influence fluid flow and/or break apart aggregated particles.

How are holograms reconstructed?

Sequoia provides two pieces of software for hologram reconstruction. One is for batch processing of holograms and is used to generate a size distribution and output automatically focused particle images. The second is for qualitative viewing of holograms and allows for manually stepping through the focused planes of the hologram.

Both programs use the Fresnel transformation to reconstruct in-focus images throughout the sample volume. Particles are then extracted and characterized from these images.

See the following paper and references therein for more information about hologram reconstruction:

Owen, R.B., Zozulya, A.A. 2000. In-line digital holographic sensor for monitoring and characterizing marine particulates. Opt. Eng. 39(8): 2187-2197.

What do the particle reconstructions look like?


Can I rent the LISST-Holo2?

Yes. Sequoia has a rental unit available. The minimum rental period is one (1) month and the first month’s rent must be prepaid in full before the instrument is delivered. Subsequent months are invoiced at net 30 days payment terms. User must pay for the return shipping to Sequoia, and insure the instrument for the full price for the duration of the rental period as well as the return shipping.

If you decide to purchase a new instrument within 90 days after the beginning of the rental period, you can apply 85% of what you already paid in rental fees towards the cost of the new instrument.

Call for a draft rental agreement.